(Reuters) – Britain’s Communications Workers Union (CWU) said on Thursday its members working in Royal Mail (RMG.L) would start a 48 hour strike on Oct. 19, after it opposed the company’s move to replace its defined benefit pension scheme.

“We have served notice on Royal Mail Group for a 48hr strike commencing 19th October,” CWU said on Twitter.

Royal Mail workers on Tuesday voted to strike, potentially threatening postal delays at Christmas. Royal Mail said then that it was committed to further talks as a matter of urgency.

The union has said Royal Mail’s move to replace the pension scheme would result in members losing on average up to a third of their future pensions.